An image processing apparatus calculates a corresponding area on input images corresponding to a focused area on a real space in which a moving object moves, generates first images by scanning the input images along a horizontal line through the corresponding area, generates two-dimensional dynamic x-t images by arranging the first images in the vertical direction in time series, extracts characteristic points on the dynamic x-t image at a time T, generates dynamic trajectory information between the characteristic point at the time T and another characteristic point at different time from the time T near the characteristic point, and determines that the characteristic point belongs to the obstacle when the dynamic trajectory information satisfies the criterion for the obstacle.